I had a S4 for a while. I had issues with newer BT headsets connecting. I find with Android devices when they start to age, they are no longer are supported with apps and hardware. Do any of your other BT devices have issues connected to the S4?

If not, I would contact support@anker.com and tell what steps you have done. They might have some better tips to get you connected or tell you if there is a compatibility issue.

I have and use an older galaxy phone and I have no bluetooth issues. I would recommend holding down both the + and - button on the earbuds to foce them to forget any connections and puts them into pairing mode. Then go into your bluetooth settings and try to add them, almost always this forces it to show up

As @Monk3e said, there are definitely versioning issues with Bluetooth. Just because a phone has Bluetooth doesn't mean it will be compatible with all Bluetooth devices. My wife had a phone that wouldn't work with BT headphones I used with my Galaxy S7. It could be the BT v4.1 issue, or maybe the SoundBuds require Bluetooth LE, etc. You need to contact @AnkerSupport to clarify the requirements and if your S4 isn't compatible (it's a pretty old phone!), you pretty much don't have any options other than to return it.

@sean_bateman I am so sorry to know your Samsung can't pair with this pair of headphones. Could you please contact support@anker.com with your serial number and order number? We will cover an 18-month warranty regarding any quality issue related. Thanks.